Brake tester



Oct. 25, 1938 J. v. H. WHIPPLE BRAKE TESTER Filed Dec. 4, 1955 65/DANGEROUS Q M 9 %WM Patented Oct. 25, 1938 V UNITED STATES PATENT OFFICEBRAKE TESTER Jack Van Horn Whipple, Sellersville, Pa., as-

signor to United States Gauge Company, Sellersville, Pa., a corporationof Pennsylvania Application December 4, 1935, Serial No. 52,908

2 Claims. (01; 264-1 I This invention relates to an instrument forFigure 1 is a front elevational view of a premeasuring and indicatingchanges in velocity in ferred embodiment of the invention. order thatsaid instrument may be utilized for Figure 2 is aside elevational viewasseen when the purpose of testing the brakesvof a vehicle, viewing Fure 1 fro t e right h for example, though the instrument is usefulFigure 3 is a sectional view taken substantially .5

for other purposes. More particularly, the inalong line 33 of Fi urevention is concerned with an instrument for Figure 4 is a sectional viewtaken substanmeasuring and indicating changes in velocity in tially o ge of Figure which use is made of a liquid column to attain Figure 5 is aview taken substanti lly a n the purposes of the instrument. a e -5 OFig re 4. 7 10 The principal purpose of thi inv nti n i to Figure 6 is afragmental sectional view taken provide an accelerometer ordecelerometer; in S s a y along e of Figure Which use is made of aliquid column as the With continued reference to the drawing inmeasuring means, that may be constructed at which like referencenumerals are employed to 15. very low cost and yet will give an accurateand denote like parts throughout the several views, easily readable indition of th r t of change the brake tester of the present inventionincludes in Velocity of a vehi le or the lik a casting ll having asubstantially rectangular Another object of the invention .is to provideface 52 provided With a diagonally eXteIlding an accelerometer ordecelerometerin which use is S 3 Which is inclined at a p e y cu 2Q madeof a U-shaped column of liquid disposed angle relative to thehorizontal. Extending rearin an inclined plane so that relatively smallw r y o the p et of Casting ace I2 s changes in the acceleration ordeceleration of a a Skirt l4 forming the e Walls'of Casting vehicle, towhich the instrument is applied, will a d e te di rearward vbehind thedia onal cause a substantial change of liquid level in the recess I3 isa ridge, l5 which mer s a its ends leg of the U-shaped column used tofurnish the into opposite corn rs o skirt W Casting I! as desiredindication of acceleration or deceleration. thus takes the formiof'eh pded O ke still another object of the inventionis to form structure W adiagonal ridge r in po ed. a part of the receptacle for the U-shapedcolumn Casting dge 5 adjacent, the rear extremity of liquid as anintegral part of the, body of the thereof is provided with a chamberorbore iii instrument, and to construct only the visible parallel toCasting face One of e bore 30 leg of the receptacle from a transparentor transbeing cloeedlv dicated at IT and the other l o nt terial, endbeing open to the exterior of the casting and The invention also aims tofurther augment s l d by means f a r m v r d pl s the change in liquidlevel in the visible liquid 001- EXtendiIlg forwardly m the ends of bore35, umn due to the inclination of the column, as |5,ahdpara11e1t0 SkirtWall L W passages 7 above stated, by constructing the'visible leg of i9and 20 of restricted diameter which terminate the column of smallcross-sectional area oomin pp e 2| ed 011 t e Cast ng at the ends paredto the cross-sectional area of the invisible 0f recess leg of thecolumn. Positioned in recess I3 is an'indicator tube 22 40 Still anotherobject of the invention is to proof transparent materiel h s ass, having40 Vide'an instrument f r measuring d indicating rearwardly offsetextremities 23 which are sealed deceleration or acceleration designed sothat the m atuttine relation ag nipples by means liquid column may beused to Show when the of rings 24 of an init ally plastic material suchi trument is 1 61, her b the in t j as a synthetic resin. The ends ofbore 25 in tube 1 5 eV W e y S rumen may 22 are in fluid communicationwith the forward 45 be applied to any supporting surface andsubsequently leveled by an adjustment included as a gndsf x g i 25m'tube 22 art of its construction is o sig y arger lame er an passagesl9 p and 20, but as seen in Figure 3, is of substantially A further obect of the invention is to provide less diameter than casting bore m iif ii eg or t i zi of the type From the structure thus far described itwill 50 u 1 izing a mu: co umn me u ng mea s to be clear that castingbore i6, restricted passage dampen obJectlonable vibrations of thecolumn. |9 and t b l bor 25, form a liquid receptacle Still furt er O jct of the invention Wi11 which is closed to the atmosphere and which, byD as the s r p n p s W h re er n means of passage 20 is made i e-entrantu on to the accompanying drawing in which: itself. The receptacle justdescribed is disposed 55 is a pair of parallel, vertically disposed lugs33 r and 34 provided with aligned apertures 35 and 36; Lugs 33 and 34are adapted to be mounted upon a pin 31 supported inaa bracket 38disposed be- 7 tween the lugs and carried by a suction cup 39.

which may be secured to a suitable part of the vehicle to be tested. Asseen in Figure 6, pin 31 is provided with a knurled head 4| adapted tobear against casting lug 33, and a threaded shank 42 adapted to bescrewed into threaded lug aperture 36 for clamping the casting lugs inadjusted position with respect to bracket 38. I

The operation of the brake tester is as follows. Suction cup 38 is firstmounted at a suitable point upon the frame of the vehicle to be testedwith passages I9 and 20 extending in the direction of motion of thevehicle and pin 3-1 disposed in a horizontal position. In testingautomobiles it has been found convenient tomount the suction cup in thevehicle windshield in front of the'drivers seat. Casting Ills thenadjusted about pin 31 until the liquid surface 28 registers with thezero" index on the casting face, under which conditions the casting faceI2 will be disposed in a vertical plane and the device will beconditioned to perform a testing operation. Under such conditions thetubes I9 and 28 will be horizontally disposed and extending in thedirection of motion of the vehicle, and bores I6 and 25' will beinclined to a horizontal reference plane and ex-; tending transverselyto the direction of motion of the vehicle.

The vehicle is next accelerated to a suitable testing speed and thebrakes applied with constant pressure. In testing automobiles it hasbeen found convenient to accelerate the vehicle to a speed from thirtyto forty miles per hour before applying the brakes, and the brakes areapplied with the maximum pressure employed in normal use.

As the brakes are applied, the vehicle will decelerate until it isbrought to rest. During such deceleration liquid 28 will gradually dropwithin tube 22 until it comes to rest at a new position and inregistration with. indicia 3| and 32. The position at which theliquidlevel comes. to rest will be determined by the value of the vehicledeceleration which is in turn determined by the retarding action of'thevehicle brakes. Liquid level 28 in registering" with indicia 31' and 32thus gives a direct indication ofthe vehicle deceleration and brakingaction, and the indicia may be respectively marked, as shown, in unitsof deceleration and terms indicating the condition of the brakes. I

Liquid level 28 is caused to drop from its .zero position when thebrakes are applied by virtue of the fact that the inertia of the liquidwithin capillary tube I9, which moves in the direction of vehiclemotion, causes the liquid to flow from the tube toward the rear of theinstrumentv where it flows into bore I8. Liquid which flows from thetube into bore I6 is replaced by liquid frorntube 22 with consequentdropping of liquid level 28.'

As the liquid column is disposed in a plane which is only slightlyinclined to the horizontal, it will-be seen that liquid in flowing fromcapillary tube I9 into casting bore I6 need overcome a pressure head inbore I6 which is relatively small due to the small vertical height ofthe a much greater drop in the liquid level 28 in tube 22,. the relativediameters of the bores being so designed that liquid level 28 in bore 25may drop from its zero position to the bottom of tube 22 withouteffecting a sufficient rise in the liquid level of casting bore I6 tocause overflow into capillary tube28. By virtue of the small liquidcapacity of indicator tube 22, displacement of a relatively small volumeof liquid'from the tube will afford a substantial drop in liquid level28 and therefore provide amplified indication in registering withindicia 3| and 32.

After the vehicle has been brought to rest, liquid level 28 will betemporarily retained in the position which it assumed when the brakeswere applied by virtue of the fact that tube I8, due to its restricteddiameter, temporarily restrains liquid from' returning to bore 25' frombore I8 when the vehicle is brought to rest and observation of theinstrument indication is thus facilitated. Passage I9, due to itsrestricted diameter, further serves to dampen oscillation of the liquidcolumn when the brakes are applied and to bring the liquid level 28 torest.

Itwill be appreciated that when the vehicle is being accelerated to testspeed, the converse of the described indicating action will occur andliquid will flow from casting bore I6 through tube I9 into bore25. Undersuch conditions liquid level 28 will rise and liquid may overflowthrough capillary tube 20 back into bore I8. When the vehicle reachestesting speed, and before the brakes are applied, the liquid column isbrought to equilibrium with liquid level 28 in its zero position.

In order to empty or replenish the supply of. liquid in the liquidcolumn, plug I8 is removed from the end of casting bore I6 and access isthen had directly to the receptacle containing the liquid column.

Although the illustrated embodiment of the invention has been describedas used for the purpose of indicating deceleration or braking action ofa vehicle, it is to be understood that the instrument may be utilized asan accelerometer for indicating the pick-up of a vehicle and such use ofthe instrumentis embraced within the scope of, the present invention.

While in the illustrated embodiment of the invention the tube 22 isstraight from end to end, it will be understood that said tube mayassume other forms. For example, a short portion between the endsthereof. may be disposed horizontally and the remaining portionsinclined and disposed diagonally of the casting. It is desirable toprovide a horizontally disposed section at the point of the level ofliquid when normal operation of the vehicle is occurring, slightdepartures from normal being thus made plainly visible by a rising orfall of the column into the inclined portions of the tube. Sucharrangement is particularly desirable when the instrument is used as anindicator of acceleration.

The invention may be embodied in otherv specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of. the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. An instrument to show acceleration or deceleration of a vehicle orthe like, comprising a casting formed to provide a rectangular fronthaving a diagonally disposed recess, and a skirt forming the side wallsof the instrument, a, chamberformed in said casting, a transparent tubedisposed in said recess and having its ends secured to said casting andin communication at opposite ends with said chamber, and liquid disposedin said tube and chamber providing a U-shaped column.

2. An indicating instrument comprising a casing having a front face,indicia on said face, flanges integral with said face and extendingrearwardly from said face and forming the side walls of said instrument,a rib integral with said face and flanges and disposed betweensaidflanges, a chamber in said rib, passages extending from said chambertoward said face, and a tube having a transparent Wall disposed so thatits ends are connected tosaid passages, said tube being disposed in arecess in said face and opposite the indicia thereon.

JACK VAN HORN WHIPPLE.

